Routing a session initiation protocol (SIP) message in a communication system

ABSTRACT

An approach that provides routing a SIP message to a proxy server of a called party in a communication network is provided. In one embodiment, there is a routing tool that assists in routing a session initiation protocol (SIP) message to a called party. The routing tool, including a receiving component, receives a SIP message of a user making a call in the network. The routing tool further includes a parsing component configured to parse the message to determine the domain of the called party and performs a table lookup using the domain of the called party in order to: retrieve a destination code; embed the destination code into the message; and route the message based on the destination code.

RELATED U.S. APPLICATION DATA

The present patent document is a continuation of U.S. patent applicationSer. No. 12/938,685 (now U.S. Pat. No. 8,417,832), filed Nov. 3, 2010,entitled “ROUTING A SESSION INITIATION PROTOCOL (SIP) MESSAGE IN ACOMMUNICATION SYSTEM”, the disclosure of which is incorporated herein byreference.

FIELD OF THE INVENTION

This invention relates generally to telecommunication networks and, morespecifically, to routing a session initiation (SIP) message in acommunication system.

BACKGROUND OF THE INVENTION

The field of telecommunications has become increasingly important intoday's society. Providing a network in which users can quickly andeffectively interact with one another presents a significant challengefor network operators. In today's communication networks, sessioninitiation protocol (SIP) plays a key role in providing multimediasessions to users. Emerging telecommunications technologies are alsoexpected to leverage SIP for its known advantages.

With the expanding number of SIP users, new protocols are needed inorder to optimize communication networks. For example, one problem oftenencountered by a network operator is how to minimize unnecessary trafficin the network. Another problem is how to reduce latency imposed byexcessive transactions among proxy servers in the network. The networkoperator seeks to effectively manage these two issues to increase thespeed and reliability of the network in order to meet the growing numberof users and their communication needs.

SUMMARY OF THE INVENTION

Embodiments of this invention are directed to routing a sessioninitiation protocol (SIP) message in a SIP environment using domainswitches (routing tools) in order to reduce unnecessary traffic andlatency in the network. Using this system, the network provider will beable to provide a more efficient network to meet the increasing demandsof a growing number of telecommunication users.

In one embodiment, there is a method for routing a session initiationprotocol (SIP) message in a communication network, comprising: receivinga SIP message; parsing the message to determine the domain of the calledparty; performing a table lookup using the domain of the called party toretrieve a destination code and Internet protocol (IP) address of aprimary destination device; embedding the destination code into themessage; and routing the message to the IP address of the destinationdevice.

In a second embodiment, there is a system for routing a sessioninitiation protocol (SIP) message in a communication network. In thisembodiment, the system comprises at least one processing unit and memoryoperably associated with the at least one processing unit. A domainswitch is storable in memory and executable by the at least oneprocessing unit. The domain switch comprises: a receiving componentconfigured to receive a SIP message; a parsing component configured toparse the message to determine the domain of the called party; a lookupcomponent configured to perform a table lookup using the domain of thecalled party to retrieve a destination code and Internet protocol (IP)address of a primary destination device; an embedding componentconfigured to embed the destination code into the message; and a routingcomponent configured to route the message to the IP address of thedestination device.

In a third embodiment, there is a computer-readable medium storingcomputer instructions which, when executed, enables a computer system toprovide routing a session initiation protocol (SIP) message in acommunication network, the computer readable medium comprising programcode for causing a computer system to: receive a SIP message; parse themessage to determine the domain of the called party; perform a tablelookup using the domain of the called party to retrieve a destinationcode and Internet protocol (IP) address of a primary destination device;embed the destination code into the message; and route the message tothe IP address of the destination device.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of this invention will be more readilyunderstood from the following detailed description of the variousaspects of the invention taken in conjunction with the accompanyingdrawings in which:

FIG. 1 shows a schematic of an exemplary computing environment in whichelements of the present invention may operate.

FIG. 2 shows an illustrative session initiation protocol (SIP)architecture diagram.

FIG. 3 shows basic services provided by SIP servers and the interactionsbetween SIP components including a domain switch according to thepresent invention.

FIG. 4 shows an illustrative communication system according to thepresent invention.

FIG. 5 shows a routing tool according to one embodiment of thisinvention that operates in the communication system.

FIG. 6 shows a flow diagram of a process for routing a SIP message to acalled party in a communication system.

The drawings are not necessarily to scale. The drawings are merelyschematic representations, not intended to portray specific parametersof the invention. The drawings are intended to depict only typicalembodiments of the invention, and therefore should not be considered aslimiting the scope of the invention. In the drawings, like numberingrepresents like elements.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of this invention are directed to routing a call to anappropriate proxy server in a communication network in order to locatethe called party using a domain switch. ‘Domain switch’ as used hereinrefers to a server plugin (program module or device) or separate devicewhich assists in the efficient routing of a SIP message to a calledparty in a communication environment by reducing the number oftransactions necessary in message delivery. Specifically, the domainswitch (routing tool) receives a SIP message of a user making a call inthe network, parses the message to determine the domain of the calledparty, performs a table lookup using the domain of the called party inorder to retrieve a destination code and IP address of a destinationdevice, embeds the destination code into the message, and routes themessage to the IP address of the destination device.

FIG. 1 illustrates a computerized implementation 100 of the presentinvention. As depicted, implementation 100 includes computer system 104deployed within a computer infrastructure 102. This is intended todemonstrate, among other things, that the present invention isimplemented within a network environment (e.g., the Internet, a widearea network (WAN), a local area network (LAN), a virtual privatenetwork (VPN), etc. Communication throughout the network can occur viaany combination of various types of communications links. For example,the communication links can comprise addressable connections that mayutilize any combination of wired and/or wireless transmission methods.Where communications occur via the Internet, connectivity could beprovided by conventional TCP/IP sockets-based protocol, and an Internetservice provider could be used to establish connectivity to theInternet. Still yet, computer infrastructure 102 is intended todemonstrate that some or all of the components of implementation 100could be deployed, managed, serviced, etc., by a service provider whooffers to implement, deploy, and/or perform the functions of the presentinvention for others.

Computer system 104 is intended to represent any type of computer systemthat may be implemented in deploying/realizing the teachings recitedherein. In this particular example, computer system 104 represents anillustrative system for routing a SIP message process. It should beunderstood that any other computers implemented under the presentinvention may have different components/software, but will performsimilar functions. As shown, computer system 104 includes a processingunit 106, memory 108 for storing a routing tool 150, a bus 110, anddevice interfaces 112.

In general, processing unit 106 executes computer program code, such asprogram code for operating routing tool 150, which is stored in memory108 and/or storage system 116. While executing computer program code,processing unit 106 can read and/or write data to/from memory 108,storage system 116, and a domain table 117. Domain table 117 stores datarelating to a plurality of domain switches. Storage system 116 anddomain table 117 can include VCRs, DVRs, RAID arrays, USB hard drives,optical disk recorders, flash storage devices, or any other similarstorage device. Although not shown, computer system 104 could alsoinclude I/O interfaces that communicate with one or more externaldevices 115 that enable a user to interact with computer system 104.

Referring now to FIG. 2, an illustrative session initiation protocol(SIP) architecture diagram 200 is depicted. SIP is a text-basedapplication-layer signaling and call control protocol used to create,modify, and terminate SIP sessions. FIG. 2 shows how communication ishandled among SIP components and how SIP components fit into a networkenvironment.

FIG. 2 depicts two companies, ACME Company 220 and ABC Company 222. ACMECompany 220 has four user agents (204A, 204B, 206A, 206B) and two SIPservers (208A, 208B). User agents are end user devices in a SIP systemsuch as cell phones, multimedia handsets, PCs, PDAs, etc. used to createand manage a SIP session. SIP server 208A is connected to Firewall 210A.ABC Company 222 has two user agents (204C, 206C) and SIP server 208Cconnected to Firewall 210B.

As shown in FIG. 2, ACME Company 220 has two SIP proxy servers (208A,208B) that direct SIP messages between domains within the company. Eachproxy server acts an intermediary entity primarily playing the role ofrouter, meaning its job is to ensure that a request is sent to anotherentity “closer” to the called party. SIP operates hop-by-hop, meaningclients do not usually communicate directly, but rather use proxiesalong the signaling path to send and receive messages. Many “hops” are,at times, necessary in determining the location of a called party,giving rise to spaghetti routes that load the network with unnecessarytraffic. Moreover, every proxy server performs a DNS (Domain NameSystem) search to get the IP (Internet Protocol) address, port, andtransport protocol of the next hop server. The present invention seeksto reduce the number of hops by routing the SIP message directly to adevice able to locate the called party.

In FIG. 2, SIP proxy server 208A connected to firewall 210A handles allSIP messages sent to recipients outside the company and all messagessent to recipients within the company from outside. For example, a SIPmessage sent from SIP client 204A in ACME Company 220 to SIP client 204Cin ABC Company 222 would be sent to SIP proxy server 208A in ACMECompany 220. SIP proxy server 208A then forwards the SIP message todestination SIP client computer 204C, or the SIP IP phone 206C, in thedomain of SIP proxy server 208C in ABC Company 222.

FIG. 3 shows communication system 300 with basic services 312 utilizedby SIP server 302 and the interactions between SIP components includingdomain switch 150. SIP proxy 302 handles SIP messages between useragents 310A and 310B. Basic SIP server/services 312 includesmaintaining/accessing data in registered users table 306 and locationdatabase 308. Registered users table 306 contains a list of all useragents within the served domain(s) (in this example, 310A and 310B).Location database 308 stores the addresses of those user agents that areregistered within registered users table 306. Location database 308 alsoprovides information about a caller's possible locations to SIP proxy302.

FIG. 3 further depicts domain switch 150 (or routing tool) whichprovides means to minimize the number of “hops” necessary in locating acalled party, thereby reducing network traffic and connection delays.Domain switch 150 serves a plurality of domains and a plurality of usersin each of the domains. Each domain switch is identified by a uniquedestination code. Each domain switch is able to access the destinationcodes and IP addresses of a plurality of other specified domainswitches. Each domain switch has links, either physical or logical, toeach of the plurality of other specified domain switches. Domain switch150 reads domain table 117 to determine how to route a SIP messagereceived by SIP proxy server 302 (described in more detail below).

FIG. 4 shows an exemplary communication system 400 using SIP accordingto one embodiment of this invention. FIG. 4 depicts three SIP-basedservice providers (410, 412, 414). Service provider 410 has user agents(408A, 408B) linked to SIP server 406A and domain switch 402A. Serviceprovider 412 has user agents (408C, 408D) linked to SIP server 406B anddomain switch 402B. Service provider 414 has user agents (408E, 408F)linked to SIP server 406C and domain switch 402C. Each domain switch islinked to super domain switch 404.

A proxy server, on receiving a SIP message, hands over the SIP messageto the local (calling party) domain switch. The local domain switchparses the SIP message to retrieve the domain of the called party. Thedomain switch performs a table lookup using the domain of the calledparty and retrieves a destination code associated with the domain switchof the called party. The domain switch wraps the message with thedestination code and routes the call to the domain switch of the calledparty.

In cases where the domain switch is unable to find the destination codeassociated with the domain of the called party during the table lookup,it wraps the SIP message with the code of a super domain switch (orsecondary device) and forwards the SIP message to the super domainswitch. The domain switch system is a hierarchical system for assistingin the routing of a SIP message to the called party. The top of thathierarchy is the super domain switch. The super domain switch holds thelist of names, destination codes, addresses, and served domains of thelower-level domain switches.

FIG. 5 shows a more detailed view of domain switch 150, which assists inrouting the message to a called party in a communication system. Thelocal SIP proxy server is the first point of contact when a call ismade. The SIP proxy interrogates the details of the message and handsthe message to a local domain switch if the SIP proxy server is unableto locate the IP address in its registered user agents table (see 306 ofFIG. 3). As shown, domain switch 150 comprises a receiving component 160configured to receive a SIP message from the proxy server. Parsingcomponent 162 parses the SIP message to retrieve the domain of thecalled party. Using the domain of the called party, parsing component162 performs a table lookup of domain table 117. An example is shownbelow for DS1 (Domain Table 1).

DOMAIN TABLE 1 Domain Destination Served Link ID Switch ID Code IPAddress Domains from DS1 DS1 2246 aa1.bb1.cc1.dd1 A1.com n/a B1.comC1.com DS2 2245 aa2.bb2.cc2.dd2 D1.com 03 E1.com F1, com DS3 2243aa3.bb3.cc3.dd3 G1.com 04 H1.com I1.com J1.com SDS1 2247 aa4.bb4.cc4.dd4Others 01

The IP address and the destination code of the domain switch associatedwith the called party are retrieved from the domain table. In thisexample, the IP address and destination code for domain switch 3 (DS3)are retrieved. Embedding component 166 embeds (or wraps) the SIP messagewith the code of DS3 (i.e., 2243). Routing component 168 routes the callto the IP address of DS3 (i.e., aa3.bb3.cc3.dd3).

In another embodiment of the present invention, in cases when the domainswitch is unable to find the destination code associated with the domainswitch of the called party when doing a domain table lookup, the domainswitch wraps the SIP message with the code of a super domain switch (orsecondary device) and forwards the SIP message to the super domainswitch. Referring back to FIG. 4, in cases when parsing component 162 ofdomain switch 402A is unable to locate the destination code of thedomain switch of a called party, embedding component 166 of domainswitch 402A embeds the destination code of super domain switch 404 intothe SIP message and routing component 168 of domain switch 402A routesthe message to super domain switch 404.

In another embodiment of the present invention, a SIP message isdelivered to a called party roaming in an area of another serviceprovider. For example, user agent 408F roams in a network outside ofservice provider 414, such as the network area of service provider 412.After authentication, user agent 408F is registered in the table ofregistered users (see 306 of FIG. 3) of service provider 412. SIP server406B contacts the domain switch associated with the home area of useragent 408F (domain switch 402C) using an appropriate method. SIP server406C updates the location of user agent 408F in location database ofregistered users (see 308 of FIG. 3). When user agent 408B calls useragent 408F, the call reaches domain switch 402C, which in turn wraps themessage with the code of the domain switch 402B (where user agent 408Fis registered currently) and routes the call to domain switch 406B. SIPserver 406B delivers the call to user agent 408F.

In still another embodiment of the present invention, when the domainswitch of the called party receives the SIP message embedded with thedestination code associated with the receiving domain switch, the domainswitch recognizes that the SIP message has arrived at the desireddestination. The domain switch hands the SIP message over to a localproxy server of the called party and the message is delivered to thecalled party. Referring back to FIG. 4, when the SIP message is receivedby DS3 (destination domain switch), the SIP message is handed over toSIP server 406C. SIP server 406C delivers the message to the calledparty.

FIG. 6 depicts the methods disclosed herein. According to oneembodiment, in step S10, identification tool 150 receives the SIPmessage of the calling party. In S11, the SIP is parsed in order toretrieve the domain of the called party. In S12, a domain table lookupis performed to retrieve the destination code and IP address associatedwith the domain switch of the called party. In S13, the destination codeis embedded into the SIP message. In S14, the SIP message is routed tothe IP address of the domain switch of the called party.

The flowchart of FIG. 6 illustrates the architecture, functionality, andoperation of possible implementations of systems, methods, and computerprogram products according to various embodiments of the presentinvention. In this regard, each block in the flowchart may represent amodule, segment, or portion of code, which comprises one or moreexecutable instructions for implementing the specified logicalfunction(s). It should also be noted that, in some alternativeimplementations, the functions noted in the blocks may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently. It will also benoted that each block of flowchart illustration can be implemented byspecial purpose hardware-based systems that perform the specifiedfunctions or acts, or combinations of special purpose hardware andcomputer instructions.

While shown and described herein as a solution for routing a SIP messageto a called party in a communication system, it is understood that theinvention further provides various alternative embodiments. For example,in one embodiment, the invention provides a computer-readable/useablemedium that includes computer program code to enable a computerinfrastructure to provide routing a SIP message functionality asdiscussed herein. To this extent, the computer-readable/useable mediumincludes program code that implements each of the various processes ofthe invention. It is understood that the terms computer-readable mediumor computer-useable medium comprises one or more of any type of physicalembodiment of the program code. In particular, thecomputer-readable/useable medium can comprise program code embodied onone or more portable storage articles of manufacture (e.g., a compactdisc, a magnetic disk, a tape, etc.), on one or more data storageportions of a computing device, such as memory 108 (FIG. 1) and/orstorage system 116 (FIG. 1) (e.g., a fixed disk, a read-only memory, arandom access memory, a cache memory, etc.), and/or as a data signal(e.g., a propagated signal) traveling over a network (e.g., during awired/wireless electronic distribution of the program code).

In another embodiment, the invention provides a computer-implementedmethod for providing routing a SIP message in a communication systemfunction. In this case, a computer infrastructure, such as computersystem 102 (FIG. 1), can be provided and one or more systems forperforming the process of the invention can be obtained (e.g., created,purchased, used, modified, etc.) and deployed to the computerinfrastructure. To this extent, the deployment of a system can compriseone or more of: (1) installing program code on a computing device, suchas computer system 102 (FIG. 1), from a computer-readable medium; (2)adding one or more computing devices to the computer infrastructure; and(3) incorporating and/or modifying one or more existing systems of thecomputer infrastructure to enable the computer infrastructure to performthe process of the invention.

As used herein, it is understood that the terms “program code” and“computer program code” are synonymous and mean any expression, in anylanguage, code or notation, of a set of instructions intended to cause acomputing device having an information processing capability to performa particular function either directly or after either or both of thefollowing: (a) conversion to another language, code or notation; and/or(b) reproduction in a different material form. To this extent, programcode can be embodied as one or more of: an application/software program,component software/a library of functions, an operating system, a basicdevice system/driver for a particular computing device, and the like.

A data processing system suitable for storing and/or executing programcode can be provided hereunder and can include at least one processorcommunicatively coupled, directly or indirectly, to memory element(s)through a system bus. The memory elements can include, but are notlimited to, local memory employed during actual execution of the programcode, bulk storage, and cache memories that provide temporary storage ofat least some program code in order to reduce the number of times codemust be retrieved from bulk storage during execution. Input/output ordevice devices (including, but not limited to, keyboards, displays,pointing devices, etc.) can be coupled to the system either directly orthrough intervening device controllers.

Network adapters also may be coupled to the system to enable the dataprocessing system to become coupled to other data processing systems,remote printers, storage devices, and/or the like, through anycombination of intervening private or public networks. Illustrativenetwork adapters include, but are not limited to, modems, cable modems,and Ethernet cards.

The foregoing description of various aspects of the invention has beenpresented for purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formdisclosed and, obviously, many modifications and variations arepossible. Such modifications and variations that may be apparent to aperson skilled in the art are intended to be included within the scopeof the invention as defined by the accompanying claims.

What is claimed is:
 1. A method for routing a session initiationprotocol (SIP) message in a communication network by a domain switch,comprising: registering a party with a first table of registered usersof a first domain, the first domain having an associated first domainswitch and the first table of registered users; receiving a SIP messagedirected to the party; parsing the message to determine a domain towhich the party is registered; performing a table lookup using the firstdomain to retrieve a first destination code and a first Internetprotocol (IP) address associated with the first domain switch; when thefirst destination code and the first IP address of the first domainswitch are not retrieved, performing a table lookup to retrieve a thirddestination code and a third Internet protocol (IP) address of a superdomain switch; when the first destination code and the first IP addressof the first domain switch are retrieved, perform the following:embedding the first destination code into the message; routing themessage to the first IP address of the first domain switch; determiningthat the party has roamed to a location associated with a second domain,the second domain having an associated second domain switch and a secondtable of registered users; updating the second table of registered usersbased on the determining; wrapping, by the first domain switch, the SIPmessage with a second destination code associated with the second domainswitch; and routing the wrapped message to the second domain switch. 2.The method according to claim 1, wherein receiving a SIP messagecomprises receiving by an input device or a communication interface of aserver device.
 3. The method according to claim 1, further comprisingrouting the message to the third IP address of the super domain switchafter the performing the table lookup to retrieve the third destinationcode and the third Internet protocol (IP) address of the super domainswitch when the first destination code and the first IP address of thefirst domain switch are not retrieved.
 4. The method according to claim1, further comprising: parsing the message for a destination code; androuting the message along an available route based on the destinationcode when a destination code is found.
 5. The method according to claim1, further comprising recognizing an arrival of the message at thesecond domain switch.
 6. A routing tool for routing a session initiationprotocol (SIP) message in a communication network, comprising: a memorymedium comprising instructions; a bus coupled to the memory medium; anda processor coupled to the bus that when executing the instructionscauses the routing tool to: register a party with a first table ofregistered users of a first domain, the first domain having anassociated first domain switch and the first table of registered users;receive a SIP message directed to the party; parse the message todetermine a domain to which the party is registered; perform a tablelookup using the first domain to retrieve a first destination code and afirst Internet protocol (IP) address associated with the first domainswitch; when the first destination code and the first IP address of thefirst domain switch are not retrieved, perform a table lookup toretrieve a third destination code and a third Internet protocol (IP)address of a super domain switch; when the first destination code andthe first IP address of the first domain switch are retrieved, therouting tool is caused to: embed the first destination code into themessage; route the message to the first IP address of the first domainswitch; determine that the party has roamed to a location associatedwith a second domain, the second domain having an associated seconddomain switch and a second table of registered users; update the secondtable of registered users based on the determining; wrap, by the firstdomain switch, the SIP message with a second destination code associatedwith the second domain switch; and route the wrapped message to thesecond domain switch.
 7. The routing tool according to claim 6 beingfurther caused to retrieve a SIP message by an input device or acommunication interface of a server device.
 8. The routing toolaccording to claim 6 being further caused to route the message to thethird IP address of the super domain switch after the performing thetable lookup to retrieve the third destination code and the thirdInternet protocol (IP) address of the super domain switch when the firstdestination code and the first IP address of the first domain switch arenot retrieved.
 9. The routing tool according to claim 6 being furthercaused to parse the message for a destination code and route the messagealong an available route based on the destination code when adestination code is found.
 10. The routing tool according to claim 6being further caused to recognize an arrival of the message at thesecond domain switch.
 11. A computer-readable storage device containinga program product for routing a session initiation protocol (SIP)message in a communication network by a domain switch, the programproduct comprising program code for causing a computer system to:register a party with a first table of registered users of a firstdomain, the first domain having an associated first domain switch andthe first table of registered users; receive a SIP message directed tothe party; parse the message to determine a domain to which the party isregistered; perform a table lookup using the first domain to retrieve afirst destination code and a first Internet protocol (IP) addressassociated with the first domain switch; when the first destination codeand the first IP address of the first domain switch are not retrieved,perform a table lookup to retrieve a third destination code and a thirdInternet protocol (IP) address of a super domain switch; when the firstdestination code and the first IP address of the first domain switch areretrieved, the program product causes the computer system to: embed thefirst destination code into the message; route the message to the firstIP address of the first domain switch; determine that the party hasroamed to a location associated with a second domain, the second domainhaving an associated second domain switch and a second table ofregistered users; update the second table of registered users based onthe determining; wrap, by the first domain switch, the SIP message witha second destination code associated with the second domain switch; androute the wrapped message to the second domain switch.
 12. Thecomputer-readable storage device of claim 11, the program productfurther comprising program code for causing the computer system toreceive by an input device or a communication interface of a serverdevice.
 13. The computer-readable storage device of claim 11, theprogram product further comprising program code for causing the computersystem to route the message to the third IP address of the super domainswitch after the performing the table lookup to retrieve the thirddestination code and the third Internet protocol (IP) address of thesuper domain switch when the first destination code and the first IPaddress of the first domain switch are not retrieved.
 14. Thecomputer-readable storage device of claim 11, the program productfurther comprising program code for causing the computer system to parsethe message for a destination code and route the message along anavailable route based on the destination code when a destination code isfound.
 15. The computer-readable storage device of claim 11, the programproduct further comprising program code for causing the computer systemto recognize an arrival of the message at the second domain switch. 16.The computer-readable storage device of claim 15, wherein a messageroute is along a dedicated physical link.
 17. The computer-readablestorage device of claim 15, wherein a message route is along a dedicatedlogical link.